Continuous positive airway pressure device and method

ABSTRACT

A continuous positive airway pressure system features a housing forming an airway chamber, and an air pressure inlet and an air pressure outlet. The housing further defines internally a pair of tapered air jets, and a pair of tapered air receivers. The air receivers are located downstream of the air supply jets and disposed coaxially with respective ones of the air supply jets. Each receiver has a taper in an opposite direction to the direction of the taper of the air supply jets. A pair of nasal prongs is located downstream of the air receiving jets. Each receiver comprises a hemispherical section that is oriented at an angle off the center line of the supply.

CLAIM FOR PRIORITY

The present application is a continuation-in-part of, and claimspriority to, U.S. patent application Ser. No. 11/966,805, filed Dec. 28,2007, the disclosure of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The invention relates to pressure airway devices and methods forsupplying pressurized air used in the field of respiratory therapy, andmore particularly to devices and methods that provide positive airwaypressure to the nasal cannula of a person or particularly an infant.

BACKGROUND OF THE INVENTION

In the field of respiratory therapy it is known to provide a continuouspositive airway pressure (CPAP) system and method for deliveringcontinuous positive airway pressure, via the nasal cannula, to personsand particularly infants. This is particularly true in the case ofprematurely born infants who frequently suffer with increased work ofbreathing due to immature lungs that have the propensity to collapseduring exhalation and resist expansion during inhalation.

One particular method of treatment involves the use of nasal cannulathat fits sealingly into the nares and are connected to a breathingsystem that generates a continuous flow of air with above atmosphericpressures, commonly referred to as continuous positive airway pressure(CPAP) therapy. The positive pressure is transmitted through theinfant's airways and into the lungs thereby preventing collapse duringexhalation and augmenting expansion during inhalation.

There are a wide variety of devices in use for CPAP. The CPAP devicesoften comprise what is referred to as a generator body, which isessentially a housing forming a chamber that receives air pressure fromtubing. The generator body typically has an exhalation port for air toescape during the exhalation phase. Further, the generator body has apair of nasal prongs which fit into the patient's nares to supplypressure into the nares.

It would be desirable to provide a CPAP device that has reduced size,improved performance, and/or other benefits with respect to the patient.Moreover, it is often desirable to be able to reduce the amount ofpressure that needs to be supplied to a CPAP device, thereby simplifyingthe structure of the associated air pump, which may have benefits withrespect to reduced size, energy consumption, sound, complexity and cost.Further, it is typically desirable to reduce the size and mass of theCPAP interface assembly which fits against the face. It may be desirableto have the head gear that attaches the CPAP device to be smaller,simpler and/or less cumbersome. It may also be advantageous to have sucha device that facilitates handling of the patient by caretakers.

SUMMARY OF THE INVENTION

Some embodiments provide a CPAP device and method that has reduced size,improved performance, and/or other benefits with respect to the patient.

An aspect of the present invention in some embodiments involves acontinuous positive airway pressure system, including a housing formingan airway chamber, and having an air pressure inlet and an air pressureoutlet, and further defining internally a pair of tapered air jets, apair of tapered air receivers each disposed coaxially with one of theair supply jets downstream of the air supply jets, and each having ataper in an opposite direction to the direction of taper of the airsupply jets, and a pair of nasal prongs downstream of the air receivers.Each receiver includes a hemispherical section that is oriented at anangle off the center line of the supply.

Another aspect of the continuous positive airway pressure system in someembodiments includes means for defining an airway chamber, and having anair pressure inlet and an air pressure outlet, and further defininginternally a pair of tapered air jets, a pair of tapered air receivingmeans, each disposed coaxially with one of the air supply jetsdownstream of the air supply jets, and each having a taper in anopposite direction to the direction of taper of the air supply jets, anda pair of nasal interacting means downstream of the receiving means.Each receiver includes a hemispherical section that is oriented at anangle off the center line of the supply.

A further aspect of the present invention in some embodiments provides acontinuous positive airway pressure method, providing air pressure to ahousing forming an airway chamber, and further defining internally apair of tapered air jets, directing air from the air jets to a pair oftapered air receivers, each disposed coaxially with one of the airsupply jets downstream of the air supply jets, and each having a taperin an opposite direction to the direction of taper of the air supplyjets, and directing air from the air receivers to a pair of nasal prongsdownstream of the air receivers. Each receiver includes a hemisphericalsection that is oriented at an angle off the center line of the supply.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an infant patient also showing a CPAPdevice according to an embodiment of the present invention in use.

FIG. 2 is an exploded view of components of the CPAP device.

FIG. 3 is a perspective view of the device of FIG. 2 in an assembledcondition.

FIG. 4 is a cross sectional view taken through line 4-4 in FIG. 3 of theCPAP device of FIG. 3.

FIG. 5 is a cross sectional view taken through line 5-5 of FIG. 4,showing a cross section of the CPAP device of FIG. 3.

FIG. 6 is a cross sectional view of a receiver portion of a CPAP devicein accordance with an embodiment of the invention.

FIG. 7 is a side view of the FIG. 6 receiver portion.

DETAILED DESCRIPTION

Some embodiments provide a CPAP device and method that has reduced size,improved performance, and/or other benefits with respect to the patient.Preferred embodiments of the invention will now be described withreference to the drawing Figures in which like reference numerals referto like parts throughout.

FIG. 1 is a perspective view of a patient using a CPAP device accordingto an embodiment of the present invention. The device 10 includes agenerator body 12 which receives positive airflow pressure from a supplytube 14. The tube 14 is pressurized by an air pressurize device which isnot illustrated. The generator body 12 also is connected to an outlettube 15.

As will be seen in FIGS. 2 through 4, in a preferred embodiment thetubing for tubes 14 and 15 does not have a circular cross section, butrather has an oval or ellipsoid cross section. This oval cross sectionof the tubes 14 and 15 some times will provide a significant benefit,where used, in several respects. First, the oval tubing provides agreater volumetric area while still reducing the diameter of the tubingin one direction, and also allows for a more compact generator housing16 as described in more detail below with respect to FIGS. 2 through 4.Second, the oval tubing has a tendency to lay flat if the patient turnshis or her head and lies on the tubing. This relatively flat contactwith the patient's head can be more comfortable and distribute theweight of the patient's head more evenly over the tubing as compared tocircular tubing. However, some other aspects of the preferred embodimentthat will be described below can still be obtained with the use ofcircular tubing.

FIG. 1 also illustrates, as will be seen in more detail in thesubsequent Figures, that the generator body 12 includes a housing 16(which has the inlet fitting 22 that connects to the tubing 14 and anoutlet fitting 23 connected to the tubing 15) and also has an exhalationport 18 which permits outlet of the exhalation air. The housing 16 isattached to a receiver assembly 20 which includes prongs that fit intothe patient's nares as will be described further below.

Turning next to FIG. 2, the housing 16 and its exhalation port 18 areillustrated. The housing 16 is essentially a rectangular box-shapedhousing having the exhalation port 18, and a pair of side structures onits side ends. The side structures each form sidewalls of the generatorbody and have the fittings 22 and 23 that receive the tubing 14 and 15,which is preferably oval tubing, as described above.

One side of the rectangular box shape of the housing 16 is open, and isadapted to receive a receiver assembly 20 which will be described inmore detail below. When the receiver 20 is mounted to close off the openend of the housing 18, a receiver cap 24 is trapped inside. The receiver20 includes a pair of nasal prongs 26 extending therefrom as well as apair of headgear attachment flanges 28 projecting therefrom. Thereceiver nasal prongs 26 may be of any suitable size and shape as issuitable for interacting with the patient's nares. In addition, theheadgear attachment flanges 28 may also be of any suitable size andshape to interact with a strap type headgear or an adhesive fasteningarrangement, or any other type of patient attachment system.

Another advantage of the oval tubing 14 and 15 is that the housing 18can have a relatively compact rectangular box shape, and the tubing 14and 15 may be arranged with its major diameter at a diagonal angle, ascan be seen by the orientation of the fittings 22 and 23, thus allowingthe tubing 14 and 15 to have a major diameter that is nearly as long asthe diagonal length of the profile of the housing 18. This contributesto the housing 18 having a desirably compact shape.

The assembly described above may be manufactured from any suitablematerials. However, in one example, the housing 18 and its fittings 22and 23, as well as the receiver cap 24, are manufactured from a plastic,such as a polycarbonate. The receiver 20, which may include the headgearattachment flanges, and nasal prongs, may be molded from a biocompatiblesilicone.

Turning next to FIGS. 4 and 5, the air flow within the CPAP device isillustrated. Supply air enters the housing 16 via a fitting 22 from apressurized source through the tubing 14. The supply air enters a supplyair channel 30 which feeds two supply air nozzle jets 32. Supply airnozzle jets 32 each generally have a first cylindrical portion 34 andthen transition to a slight outward taper region 35. The tapered portion35 is an outward flared conical taper with an included angle ofapproximately 4 degrees between the sidewalls. This outward taper hasbeen found to provide a venturi effect which is beneficial to theairflow.

In addition to having a 4 degree included angle in the tapered portion35, the axial length of the portion 35 is approximately two times thestarting diameter, i.e., the internal diameter of the cylindricalportion 34 of the jet 32. This taper improves the efficiency of thenozzle and reduces the pressure required to drive the generator.

The jets 32 direct air towards the receiver cap assembly 24, and moreparticularly to two funnel shaped receivers 38. The nasal prongs 26 thenreceive air directly from the receivers 38. The receivers 38 each have aconically tapered portion 39 with an inward flared cone having anincluded angle of 60 degrees between the sidewalls. A straightcylindrical portion 41 extends from the end of the conical portion 39.

In one preferred embodiment, a distance D from a reference line A, whichis the outlet end face 36 of the jet 32 relative to reference line B,which is the end face of the conical portion of the receivers 38, hasbeen found to be 1.8 times the internal diameter of the cylindricalportion 34 of the jets 32.

The outlet fitting 23 leads to outlet tubing by which the patientpressure can be monitored at an outlet side of the device, i.e.,pressure monitoring system that is not shown.

FIG. 5 is a cross section view showing at a different angle some of thevarious components referred to above using the same reference numerals.

FIG. 6 depicts an embodiment of the receiver 20 which improves theresistance to exhalation by the patient. The illustrated receiver 600has a hemispherical section 605 that is oriented at a 15 degree angleoff the center line of the supply. The 15 degree angle extends towardsan outlet, e.g., an exhalation port 610, providing the exhaled gas a lowresistance path thereby reducing expiratory work of the patient while heor she is breathing. A receiver cap 615, a jet 620, and a supply airchannel 625 are included in the receiver 600, which are similar infunction to the receiver cap 24, jet 32, and supply air channel 30 ofFIGS. 2-5.

It should be apparent that the FIG. 6 configuration is different fromthe configuration of FIG. 4, in which the receivers 38 were eachprovided with a conically tapered portion 39 with an inward flared conehaving an included angle of 60 degrees between the sidewalls. Also inFIG. 4, a straight cylindrical portion 41 was provided to extend fromthe end of the conical portion 39.

Turning now to FIG. 7, FIG. 7 illustrates a computation fluid dynamicmodel having lines that demonstrate the design during simulatedexhalation. It should be appreciated that an input portion 705 passeseasily to the exhalation port 610 during an exhalation portion of apatient's breathing cycle, while a jet portion 710 passes through thejet 620 to an output portion 715 through the supply air channel 625.

As can be easily understood by the figures, all surfaces of thedisclosed invention can have sharp edges removed to take advantage ofthe “Coanda” effect. The Coanda effect is the tendency of a movingfluid, either liquid or gas, to attach itself to a surface and flowalong said surface.

As a fluid moves or flows across or along a surface, a certain amount offriction (called “skin friction”) occurs between the fluid and thesurface, which can cause resistance between the fluid and the surface,causing the fluid flow to be slowed. This resistance to the flow of thefluid pulls the fluid towards the surface, causing it stick to thesurface. Thus, a fluid emerging from a nozzle tends to follow a nearbycurved surface—even to the point of bending around corners—if thecurvature of the surface or the angle the surface makes with the streamis not too sharp. The Coanda effect was discovered in 1930 by HenriCoanda, a Romanian aircraft engineer.

The design should have no impact on the efficiency of the device togenerate a stable patient pressure but should have a substantial effecton reducing the expiratory work of breathing. The expiratory work ofbreathing is the amount of work the patient must expend in order toexhale. It should be appreciated that this new angle provided unexpectedresults over the previously used angle of sixty (60) degrees, as thesixty degree angle had long been used and thought to be most favorable.Accordingly, there was a long-felt need for a configuration in which theexpiratory work of breathing would be decreased, which has beenaddressed by embodiments of the present invention.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

1. A continuous positive airway pressure system, comprising: a housingforming an airway chamber, and having an air pressure inlet and an airpressure outlet, and further defining internally a pair of tapered airjets; a pair of tapered air receivers each disposed coaxially with oneof the air supply jets downstream of the air supply jets, and eachhaving a taper in an opposite direction to the direction of taper of theair supply jets; and a pair of nasal prongs downstream of the airreceivers, wherein each receiver comprises a hemispherical section thatis oriented at an angle off the center line of the supply.
 2. The systemof claim 1, wherein the hemispherical section is oriented between anintake port and an outlet.
 3. The system of claim 2, wherein the angleis 15 degrees.
 4. The system of claim 1, wherein the air supply jetseach have a portion with an outward taper in the direction of air flow.5. The system of claim 1, wherein: the air supply jets each have aportion having a minimum internal diameter of the air supply jet, and aterminal end face; the tapered portion of the air receivers has aterminal downstream end; and a distance between the terminal end face ofthe air supply jets and the terminal downstream end is approximately 1.8times the minimum internal diameter of the air supply jets.
 6. Thesystem of claim 1, wherein the housing includes an inlet fitting that isadapted to receive tubing for supply air.
 7. The system of claim 6,wherein the inlet fitting has an oval profile and the tubing has an ovalcross section.
 8. The system of claim 1, wherein the housing has anoutlet fitting that is adapted to receive tubing so that internalpressure in the chamber of the body may be measured via the outletfitting.
 9. The system of claim 8, wherein the outlet fitting has anoval profile and the tubing has an oval cross section.
 10. A method ofproviding continuous positive airway pressure system, comprising:providing air pressure to a housing forming an airway chamber, andfurther defining internally a pair of tapered air jets; directing airfrom the air jets to a pair of tapered air receivers, each disposedcoaxially with one of the air supply jets downstream of the air supplyjets, and each having a taper in an opposite direction to the directionof taper of the air supply jets; and directing air from the airreceivers to a pair of nasal prongs downstream of the air receivers,wherein each receiver comprises a hemispherical section that is orientedat an angle off the center line of the supply.
 11. The method of claim10, wherein the hemispherical section is oriented between an intake portand an outlet.
 12. The method of claim 11, wherein the angle is 15degrees.
 13. The method of claim 10, further comprising directing airflow through a portion of the air supply jets each having an outwardtaper.
 14. The method of claim 10, wherein: the air supply jets eachhave a portion having a minimum internal diameter of the air supply jet,and a terminal end face; the tapered portion of the air receivers has aterminal downstream end; and a distance between the terminal end face ofthe air supply jets and the terminal downstream end is approximately 1.8times the minimum internal diameter of the air supply jets.
 15. Themethod of claim 10, wherein the housing is provided with an inletfitting that is adapted to receive tubing for supply air.
 16. The methodof claim 15, wherein the inlet fitting has an oval profile and thetubing has an oval cross section.
 17. The method of claim 10, whereinthe housing is provided with an outlet fitting that is adapted toreceive tubing so that internal pressure in the chamber of the body maybe measured via the outlet fitting.
 18. A continuous positive airwaypressure system, comprising: means for defining an airway chamber, andhaving an air pressure inlet and an air pressure outlet, and furtherdefining internally a pair of tapered air jets; a pair of tapered airreceiving means, each disposed coaxially with one of the air supply jetsdownstream of the air supply jets, and each having a taper in anopposite direction to the direction of taper of the air supply jets; anda pair of nasal interacting means downstream of the receiving means,wherein each receiver comprises a hemispherical section that is orientedat an angle off the center line of the supply.
 19. The system of claim18, wherein the hemispherical section is oriented between an intake portand an outlet.
 20. The system of claim 19, wherein the angle is 15degrees.